Control switch for power operated hand machines



March 28, 1967 BRENZEN 3,311,728

CONTROL SWITCH FOR POWER OPERATED HAND MACHINES Filed May 6, 1955 INV E NTOR Timoihy Brenzen United States Patent 3,311 728 CONTRGL SWITCH FOR POWER OPERATED HAND MACHINES Timothy Bremen, Red Lake, Ontario, Canada Filed May 6, 1965, Ser. No. 456,893 2 Claims. (Cl. 200-157) The invention relates to power operated hand machines, such as chain saws, wherein an internal combustion engine is the motive power. Such machines are dangerous if the operator loses control of same, so means are provided to short the ignition of the engine, if the operators hand releases the handle. However, such shorting is annoying if the machine requires test operation in a workshop, or the operator wishes to change his hand grip for any reason, such as to cut vertically instead of horizontally, or vice versa.

The principal object of the present invention is: to provide an electric switch on the handle of said machine, normally adapted to short the ignition of the engine should the operators hand accidentally release the handle, and such that means on said handle can be manually operated to remove said short, to re-start the engine.

A further object of the invention is: to design said release such that the operator can actuate same while the engine is running, to maintain said operation while he deliberately releases his grip on the handle.

A further object of the invention is: to design a handle for quick attachment of said switch thereto, and such that the two can be provided as a kit for replacement of the present handle on the machines.

A further object of the invention is: to design the invention such that two switches can be connected and used on the handle of a power saw, one to protect the operator when making vertical cuts, and the other to protect when making horizontal cuts with said saw.

Still further objects of the invention are: to construct the invention in a simple, economical and rugged manner, for mass production, simplicity of operation, low cost manufacture, and many years of satisfactory service.

With the above important and other minor objects in view, which will become more apparent as the description proceeds, the invention consists essentially in the construction and arrangement of the various parts hereinafter more particularly described, reference being bad to the accompanying drawings, wherein like characters of reference indicate corresponding parts in the several figures, and wherein:

FIGURE 1 is a perspective view of a power chain saw with the switch attached to the handle thereof, and the connection to the ignition shown in dotted outline.

FIGURE 2 is a face view of the upper part of the power saw handle and showing the switch connected therein.

FIGURE 3 is an enlarged cross section at the line 3-3, of FIGURE 2.

FIGURE 4 is an enlarged side view of the switch, with cover removed.

FIGURE 5 is an enlarged cross section taken on the line 5-5 of FIGURE 2.

FIGURE 6 is an enlarged cross sectional view through the switch electrode unit.

The supporting handle of a chain saw is usually tubular, and of a relatively U-shape, such as shown at 10 in FIGURE 1, the free ends thereof (not shown) being secured to the saw 10'. In the present invention, the tubing at the upper hand gripping portion of the handle is slit and opened up to receive the present switch therein, as shown in FIGURES 3 and 5.

The casing of the switch is in two pieces, a molded body portion 11 and a cover 12. The body 11, as shown 3,311,723 Patented Mar. 28, 1967 in FIGURE 4, is hollowed out at 13 to reduce weight, and the right hand end thereof receives the working parts. The cover 12 is the same profile as the body, lays there over, and the two are secured together by screws 14 which threaded into the body at 15. Both the cover and the body have their upper portions machined away, as at 16, for entrance into the handle 10 in a neat fit, as indicated in FIGURES 3 and 5 and dotted outline in FIGURE 2, the same being held to the handle by screws 17, which thread into the tapped holes 18. The exposed corners of the switch are rounded, as at 19, to form a smooth hand grip.

A cylindrical insulator 2G is shown in FIGURE 6. This insulator is cross drilled for the pressed reception of a contact electrode 21, which projects slightly therefrom, the two forming an electrode unit. A hole is drilled down through the centre of the insulator, and through the electrode, so a plug 22, on the end of an insulated wire 23, can be pressed theredown for connection with the electrode. A circular hole 24 is machined in the right hand end of the switch body, and partly through the hollowedout portion 13, so the unit, with wire attached can be pressed therein, with the electrode 21 positioned at the hollowed-out portion mentioned, and as shown in FIG- URE 4. In this insertion, the wire 23 will be positioned in a groove 25 for passage out of the switch and down the tubing of the handle, as shown in FIGURE 2. The other end of the wire 23 will pass out of the tubing through a suitable hole (not shown) for connection with the ignition circuit of the engine (not shown).

A switch lever 26 is centrally and pivotally mounted on a pin 27 in the switch casing, and with one end thereof protruding at an angle from the casing, as a trigger 28. A spring wire 29 is wound around the pin 27, with one end held against a wall of the casing body and the other end pressing the trigger 23 downwardly. The opposite end of the lever 26 is downwardly arced, as at 30, within the casing, and the extreme end of the arc presents a finger 31 for connection with the electrode 21 at one end of the pivot swing. The central part of the wall of the arc is outwardly tapered, as indicated at 32.

The back of the casing body, opposite the are of the lever 26, is provided with an outer extending boss 33, and a hole is centrally bored therealong from the hollowed-out portion of the body, to form a cylinder 34. A coil spring 35 rests in the bottom of this cylinder and is compressed by a control pin 36. The control pin is formed with an end piston 37 for sliding movement in the cylinder 34 and compression of the spring 35. An outwardly expanding tapered section 38, corresponding to the tape 32, is positioned adjacent the piston, and the enlarged end thereof terminates in a ledge 39 around a shaft 46 of the control pin. This shaft extends across the hollowed-out portion 13 of the casing, passes through a hole in the casing cover 12, and the emerging end of this shaft is pressed into a thumb-operable button 41. It should be mentioned at this time that the small end of the tapered section 38 is of less diameter than the shaft 40.

By observing the positions of the parts shown in FIG- URES 4 and 5 it will be seen that the arced portion 30 of the lever 26 is overlying the ledge 39 of the control pin 36, and maintaining the spring 35 compressed. At this time, the shaft 40 is holding the finger 31 of said arced portion just clear of the electrode 21, to prevent electric connection. If the operator grasps the handle 10 to lift the power machine, his fingers will press the trigger 28 of the lever 26, and the arced portion 30 will move down and release from the ledge 39. Accordingly, the control pin 36 will end-shift under pressure from the coil spring 35, to bring the tapered section 33 opposite the tapered centre 32. If the engine is driving the said machine, and the operator continues to hand support the trigger 28, the said engine will continue to operate, as the finger 31 will still be clear of the electrode 21. However, should the machine kick-back, such as from the saw contacting a knot, or if the operator should stumble over something on the ground, or if the operator should lose control of the handle for any other reason, the lever 26 will swing down under the pressure of the spring 29. In so doing, the tapered centre 32 will swing up, and the small diameter of the tapered section 38 will let it move farther in, so the finger 31 can contact the electrode 21, thus electrically shorting the wire 23 and the ignition of the engine to the handle 10, and said engine will stop.

If the operator wishes to remove the above electric short, he merely presses the button 41. The control pin 36 will accordingly move back to again compress the spring 35, while the tapered section 38 will move the arced portion 30 of the lever 26 down until it clicks back up behind the ledge 39, thus releasing the finger 31 of said lever from the electrode 21. The parts will then again be in the position shown in FIGURE 5. On the other hand, if the power machine is operating, and the operator wishes to release the handle 10, and still keep the engine running, he can press the button 41 with his thumb, against the resilience of the spring 35, and hold it pressed, until his finger releases the trigger, so the arced portion 30 can catch on the ledge 39.

In view of the above disclosure, it will be seen that as long as the operator has manual control of the handle of the machine, the ignition of the engine will remain normal for power operation, but as soon as the handle is released, this ignition will be shorted to stop the engine, and protect the operator against accident, unless of course the operator deliberately thumb presses the re-set button 41 to maintain it running.

When a power machine can be supported at two different gripping positions, such as for vertical and horizontal cuts of a chain saw, an extra switch can be placed on the handle at the position for the other grip. This extra switch will be installed in the same manner, and the wire 23 will be connected to both of the electrodes 21. The switch not under manual control will obviously be in the re-set position, shown in FIGURE 4. The other switch will then operate in the manner above explained, and as if the second switch was not there.

Cit

\Vhat I claim as my invention is:

1. A control switch for power operated hand machines, comprising: a casing; an insulated fixed electrode mounted in the casing, and for electrical connection with an engine ignition system; a resiliently actuated finger pivotally mounted in the casing and normally acting to swing into contact with the electrode, to short said ignition connection; a tapered cross pin slidably mounted in the easing, adjacent said finger; a compressed spring between one end of said cross pin and the casing; means for manually end-shitting said cross pin, against said compressed spring, to pivot the finger out of contact with the electrode, by the cam action of the taper of the cross pin therepast, and for latching of the finger behind a ledge on said cross pin; and manually operable means on said finger for moving and releasing same from said latching.

2. In combination with a hand operable power tool; a handle and control switch therefor, comprising: a metallic tubing for electrical connection with and support of said tool; a handgrasping portion of said tubing split outwardly to form an opening thereto; a switch having a metallic casing receivable in said opening and electrically secured to said tubing; an insulated fixed electrode mounted in the casing and electrically connected with the engine ignition system of said power tool; a resiliently actuated finger pivotally mounted in the casing and normally acting to swing into contact with the electrode to short said ignition system through the casing and said handle; a tapered cross pin slidably mounted in the casing, adjacent said finger; a compressed spring between one end of said cross pin and the casing; means for manually endshifting said cross pin, against the compression of said latter spring, to pivot the finger out of contact with the electrode, by the movement of said cross pin taper therepast, and for latching of the finger behind a ledge on said cross pin; and said finger operable, in the manual grasping of said handle, to release from said latching for return of said cross pin to its original position by pressure from said latter spring.

No references cited.

ROBERT K. SCHAEFER, Primary Examiner.

0 H. I-IOHAUSER, Assistant Examiner. 

1. A CONTROL SWITCH FOR POWER OPERATED HAND MACHINES, COMPRISING: A CASING; AN INSULATED FIXED ELECTRODE MOUNTED IN THE CASING, AND FOR ELECTRICAL CONNECTION WITH AN ENGINE IGNITION SYSTEM; A RESILIENTLY ACTUATED FINGER PIVOTALLY MOUNTED IN THE CASING AND NORMALLY ACTING TO SWING INTO CONTACT WITH THE ELECTRODE, TO SHORT SAID IGNITION CONNECTION; A TAPERED CROSS PIN SLIDABLY MOUNTED IN THE CASING, ADJACENT SAID FINGER; A COMPRESSED SPRING BETWEEN ONE END OF SAID CROSS PIN AND THE CASING; MEANS FOR MANUALLY END-SHIFTING SAID CROSS PIN, AGAINST SAID COMPRESSED SPRING, TO PIVOT THE FINGER OUT OF CONTACT WITH T HE ELECTRODE, BY THE CAM ACTION OF THE TAPER OF THE CROSS PIN THEREPAST, AND FOR LATCHING OF THE FINGER BEHIND A LEDGE ON SAID CROSS PIN; AND MANUALLY OPERABLE MEANS ON SAID FINGER FOR MOVING AND RELEASING SAME FROM SAID LATCHING. 